In a recent case in Alabama, the Defendant tried to exclude the opinion of a medical expert witness by stating that the expert cannot prove causation. The psychiatrist expert witness was able to withstand the challenge because of his qualifications, use of reliable methods, and his ability to provide sufficient evidence.

The Plaintiff developed a rare skin disease after receiving treatment at a county hospital. She brought a civil action claiming that the hospital and the doctors committed medical malpractice. District Judge Myron H. Thompson of the U.S. District Court, Middle District of Alabama, entertained the defendant’s motion to exclude the expert opinions of several doctors.

The judge denied the challenge, holding that neither argument conformed to “the dictates of Daubert or the realities of modern science.”

The Defendant wanted to exclude the opinion of the psychiatrist expert witness, and they emphasized that the doctor could not describe the mechanism by which Lamictal caused SJS or TEN. The judge ruled that this argument was wrong as a matter of law, because there was no requirement that the plaintiff must prove the biological means of injury. Although the Plaintiff must prove specific causation to the satisfaction of the trier of fact, this is not the same as proving the specific bodily interaction or mechanism which underlies that causation. Such a stringent standard, the judge reasoned, would eliminate testimony on even well-known cause-effect relationships.

The Defendant next argued that, even if the Plaintiff did not have to prove the exact mechanism, the experts’ admission that no double-blind study confirmed causation requires the exclusion of their opinions. The judge cited to case law that rejected this argument. In Gess v. United States (M.D.Ala. 1997), the district court confronted a case where there was no conclusive clinical study on the cause-and-effect mechanism of a particular drug, and most of the articles supporting the expert’s theory relied on animal testing. Even so, the court noted that a conclusive clinical study was not needed as long as the expert used a reliable methodology to make conclusions from known information. In that case, such a study would be “unethical under the tenets of modern medicine.”

The fact that a theory is untestable does not necessarily make it unreliable, but it does require the judge analyze the reliability of the testimony. The psychiatrist expert witness and the other medical expert testified that such a double-blind study would also be unethical in this case. The Defendant did not dispute this conclusion. Since, unethical human testing is not a prerequisite under Daubert, the judge rejected this argument.

The Defendant argued that the psychiatry expert did not have the qualifications to be an expert on causation. In particular, he argued that, because the doctor was not an expert on SJS or TEN and has not been involved in any research on the subject, he could not be an expert on whether Lamictal causes SJS or whether the Plaintiff’s taking Lamictal caused her SJS.

Judge Thompson noted the psychiatrist’s past experience and that the magistrate judge’s opinion reviewed his resume in depth. Nonetheless, Judge Thompson pointed out that the psychiatrist emphasized in the Daubert hearing that he routinely prescribed Lamictal in his practice and that his primary work was in psychopharmacology—the study of the use of medication treating mental disorders. The psychiatrist was a member of the American Society of Clinical Psychopharmacology. In the Daubert hearing, the psychiatrist testified that as a psychopharmacologist, he specializes in “what the body does to medication … [and] what medications do to the body.”

The Defendant admitted at the hearing that this qualified the psychiatrist expert to testify as to the standard of care on what dosage of Lamictal should be administered but argued that the doctor could not address causation. There is a difference between heeding warnings and understanding causation, the Defendant claimed. Judge Thompson doubted the general principle that the Defendant proposed—that an expert in the standard of care would require additional expertise to understand causation, and, ruled that it did not apply here. The question of whether the doctor relied on the right literature, the judge held, goes towards his methodology rather than his qualifications.

Regardless, the judge ruled that the psychiatrist was qualified as an expert witness based on his work: he not only prescribed Lamictal regularly, but also devoted a large portion of his work to understanding psychopharmacology. He read literature on Lamictal and relied on the knowledge of its potential side effects in prescribing it to patients. The next question was whether the psychiatrist was qualified to testify that McBride’s increased dosage of Lamictal caused the development of SJS or TEN. The Defendant argued that the psychiatrist was not a dermatologist and could not diagnose SJS or TEN.

Judge Thompson agreed with this argument—but only to a point. The psychiatrist was not qualified to identify SJS from pictures or treat it, and he admitted this in the hearings as much, stating “I don’t know about skin rashes. If I see one, I’ll send a patient to the emergency room probably.” However, Judge Thompson noted that after a specialist’s diagnosis SJS or TEN, the psychiatrist was qualified to testify on why Lamictal caused it as opposed to another drug or cause, because he could eliminate other causes by examining the patient’s history.

As a result, the judge held that the psychiatrist expert was qualified to testify to both general and specific causation.

The Defendant next challenged the psychiatrist’s methodology as unreliable. Citing the reasoning in Gess, the judge explained that the court must first identify the basis of the expert’s testimony and then decide whether the methods, procedures, and information used by him to reach his conclusions are scientifically reliable. At the Daubert hearing, the psychiatrist testified that, in forming his opinion, he considered the medical records and depositions in the case, his experience prescribing Lamictal in his practice, and several articles that he had either read in the past or reviewed for this case. He admitted that no double-blind scientific studies had conclusively established that higher initial dosages of Lamictal cause SJS or TEN. However, Judge Thompson, citing Daubert, said that the subject of an expert’s testimony need not be known to a certainty for that testimony to be admissible. Again, referencing Gess, in order for the psychiatrist’s testimony to be admissible, Judge Thompson held, he must take what is known—however large or small that body of knowledge may be—and draw his conclusions from that knowledge using the scientific method.

Judge Thompson then asked rhetorically, What, then, did the psychiatrist know? The doctor knew from the studies he read that Lamictal could cause SJS and TEN.

The psychiatrist explained at the Daubert hearing that the data showed a decrease in SJS and TEN rates from a rate of 8 in 10,000 patients taking lamotrigine to 1.6 in 10,000 patients. Finally, the psychiatrist cited from the Journal of Clinical Psychiatry, which also noted that serious rash occurs more frequently at higher dosages.

The psychiatrist confirmed that the study Journal of Clinical Psychiatry was published in a peer-reviewed journal and stated that he believed the other studies he cited were also in peer-reviewed journals. Judge Thompson credited the expert’s testimony, as he had no reason to doubt him. The Defendant did not contest that any of the journals were not peer-reviewed in the depositions, briefing, or cross-examination in the Daubert hearing. Given these articles, and the testimony of the psychiatrist, the judge concluded that this was not a niche view with minimal support. Instead, it was one with wide support in the relevant community of experts. Judge Thompson, commenting on another decision, added that “medical literature can show that a particular theory has gained general acceptance in the relevant medical community, provided the literature offers reliable data in support.”

With the articles providing the scholarly background, the psychiatrist examined the medical records and depositions. In accepting the diagnosis of SJS and TEN from the medical records, the doctor used differential diagnosis to find that Lamictal was the probable cause.

The Eleventh Circuit explained that “[d]ifferential diagnosis is conducted by determining the possible causes for the patient’s symptoms and then eliminating each of these potential causes until reaching one that cannot be ruled out or determining which of those that cannot be excluded is the most likely.” Under this method, an expert “must provide a reasonable explanation as to why he or she has concluded that [any alternative cause suggested by the defense] was not the sole cause of the plaintiff’s injury.”

Judge Thompson held that the psychiatrist expert engaged in an adequate differential diagnosis. The Plaintiff presented sufficient evidence with the psychiatrist’s expert testimony and articles at the Daubert hearing which demonstrated that this method was used in the general scientific community to diagnose the cause of SJS/TEN. In sum, the court found that the psychiatrist’s qualifications were acceptable and his methodology reliable on both standard of care and causation. His testimony was not excluded.

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